//this引用
public class Date {
    public int year;
    public int month;
    public int day;

    public void setDay(Date this,int year,int month,int day)//默认有一个参数this(Date this,int year,int month,int day)
    {
        this.year=year;
        this.month=month;
        this.day=day;
    }
    public void printDate()
    {
        System.out.println(this.year+"/"+this.month+"/"+this.day);
    }

    public static void main(String[] args) {
        Date d=new Date();
        d.setDay(2023,2,20);
        d.printDate();
    }

}
